(decamethylenedithio)dialanine compounds



United States Patent 3,444,222 (DECAMETHYLENEDITHIO)DIALANINE COMPOUNDS Carleton W. Roberts, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware N0 Drawing. Filed June 22, 1966, Ser. No. 559,404 Int. Cl. C07c 149/24 US. Cl. 260-481 Claims ABSTRACT OF THE DISCLOSURE The present invention is directed to a (decamethylenedithio)dialanine compound of the formula:

The present invention is directed to a (decamethylenedithio)dialanine compound of the formula:

Gmm-pa-cia-sllo E, Nliz 2 and its hydrohalide addition salt. In the above and succeeding formulae, R represents hydrogen or loweralkyl. In the present specification and claims, the term loweralkyl is employed to designate alkyl radicals being of from 1 to 4, both inclusive, carbon atoms, and the term hydrohalide is employed to designate hydrochloride, hydrobromide, and hydriodide, only. The products of the present invention are crystalline solid materials, typically existing as finely divided powders. They are generally useful as herbicides to control the growth of plant organisms; in particular, they are useful as agents to control the growth of bacteria and fungi, including Aspergillus terreus and Candida pelliculosa. They are also useful as substrates in the practices of vapor phase chromatography.

Those products of the present invention wherein R represents hydrogen are prepared by the reaction of cysteine:

11 013-4 H-CHr-SH with decamethylene dibromide:

Br \OHi/mBr in the presence of a sodium salt, typically sodium bicarbonate. The cysteine may be employed, at least initially, in the form of its hydrohalide addition salt. The reaction is conveniently and preferably carried out in water as a reaction medium. The reaction consumes the reacting materials in amounts which represents two molecular proportions of cysteine and one molecular proportion of the decamethylene dibromide, and the use of the reactants in such amounts is preferred. The amount of sodium bicarbonate or other sodium salt employed is not critical; however, higher yields of the desired product are obtained when the reaction medium is maintained during the course of the reaction at a pH of about 79;v accordingly, it is preferred that the sodium bicarbonate, or other sodium salt, be employed in an amount sufiicient to maintain the reaction mixture at a pH of about 7-9. The reaction goes forward readily under temperatures of a wide range with the preparation in the reaction mixture of the desired product wherein R represents hydrogen and of sodium salt, water, and carbon dioxide as byproducts. Generally, however, it is preferred to conduct the reaction at temperatures of from 10 C. to 100 C., or, yet more preferred, at temperatures of from 0 (C. to C.

The products of the present invention wherein R represents hydrogen are of moderate solubility in organic solvents and of low solubility in Water; accordingly, such products typically precipitate in the aqueous reaction mixture or become a separate liquid phase. Separation from the reaction mixture, as well as from the byproduct salt soluble therein, is readily achieved by filtration or by decantation. Higher yields are obtained if, prior to separation, the reaction mixture is acidified to a pH of about 3 to 5, conveniently by addition of an amount of acetic acid. The separated product can be employed directly for the useful purposes of the present invention, or, if desired, can be purified before being so employed. The reaction normally results in the preparation of a small amount of cystine, which has the following formula:

(HO-fi-CH-CHr-S O l lHz This substance is essentially insoluble in water and therefore precipitates with the desired product. If it is desired to separate cystine, such separation is conveniently achieved in procedures which comprise the suspension of the precipitated product material in water with ammonium hydroxide, the addition to the resulting aqueous suspension of sufficient potassium cyanide to convert the cystine to cysteine, a reprecipitation of the product with acid, and separation by filtration. In addition, the product can also be purified in more conventional procedures, notably by washing with water.

Upon analysis, it has been found that the products of the present invention wherein R reperesents hydrogen and wherein the nitrogen does not participate in a hydrogen halide addition salt ordinarily exist in an ionized such form being known generally as a Zwitterion.

The hydrohalide addition salts of those products wherein R represents hydrogen, which salts are of the following formula:

(9 halide 2 3 acid. The reaction consumes the reactants in amounts representing equimolecular proportions, and the use of the reactants in such amounts is preferred. The reaction is carried out in the presence of an inert liquid reaction medium; typically, the reactants are mixed in a loweralkanol, and diethyl ether then added in an amount sufficient to precipitate the desired hydrohalide addition salt. The salt is then separated by filtration, and, if desired, purified by conventional procedures.

Those products of the present invention wherein R represents loweralkyl are prepared by reacting the corresponding product wherein R represents hydrogen with a loweralkanol of the formula H-O-loweralkyl. The reaction is carried out in accordance with those procedures generally employed in Fischer type esterification reactions. In the instance of the preparation of products of the present invention by this route, it is generally preferred to employ a ten to twenty fold excess of the loweralkanol reactant and sufiicient hydrogen chloride gas to saturate the solution. The reaction goes forward under temperatures of a wide range, such as from --10 C. to 100 C. However, in the preparation of the present products, it has been found preferable to heat the reaction mixture to the reflux temperature of the loweralkanol and maintain the reaction mixture thereat for a period of time; to thereafter cool the reaction mixture to about C. and resaturate with hydrogen chloride; and to then repeat the process. The reaction results in the preparation of the desired product, as the hydrohalide addition salt, in the reaction mixture. Water is produced as byproduct, and there frequently remains in the reaction mixture a small amount of the acid.

The products wherein R represents loweralkyl are generally very soluble in water and the loweralkanols; hence, such products are conveniently separated by evaporation of the reaction medium under subatmospheric pressure. The resulting separated product can be purified in conventional procedures, most typically by redispersing the product in a quantity of the loweralkanol concerned and redistilling the resulting dispersion to separate the purified product.

The products of the present invention are subject to optical isomerism. The cysteine which serves as a starting material for the products is itself available in either form or as a racemic mixture. Inasmuch as none of the subsequent reactions to prepare the products of the present invention effects the isomerism, products having either form, as well as products representing a racemic mixture, can be prepared in accordance with the foregoing teaching. All such products, regardless of form, are useful for the purposes taught for the present in vention.

When it is desired to employ those products wherein R represents loweralkyl in the free amine form, the corresponding hydrohalide addition salts are reacted in conventional procedures with sodium hydroxide. The reaction is carried out in the presence of an inert liquid reaction medium and consumes the reactants in amounts representing equimolecular proportions. Preferably, the reaction is carried out by dissolving the corresponding hydrohalide addition salt in water, adding diethyl ether to obtain a two-phase system, adding the sodium hydroxide, and then shaking the resulting mixture. Thereafter, the diethyl ether solution is decanted and the diethyl ether removed by evaporation under subatmospheric pressure to separate the free amine product. The product thus obtained can be purified by conventional procedures.

The following examples illustrate the present invention and will enable those skilled in the art to practice the same.

Example 1.-3 ,3'- (decamethylenedithio dialanine To a solution of L-cysteine hydrochloride monohydrate (86.6 grams; 0.5 mole) in 400 milliliters of water was added a saturated solution of sodium bicarbonate (500 milliliters). The resulting mixture had a pH of 6. Decamethylene dibromide (79.5 grams; 0.265 mole) and ethanol (2 liters) were added. Thereafter, additional sodium bicarbonate solution was added to the reaction mixture to give a pH of about 7.8. All of the foregoing operations were carried out at room temperature. The reaction mixture was then heated to reflux temperature of about C., additional sodium bicarbonate being added during the heating to maintain the pH in the range of 7.8 to 8.2. Reflux was continued for ten hours; thereafter, the reaction mixture was permitted to cool to room temperature under nitrogen and glacial acetic acid added to the cooled mixture over a period of several hours to obtain a final pH of about 5. As a matter of convenience, the reaction mixture was permitted to stand overnight at room temperature and under nitrogen, and then filtered to separate the desired 2,2-(decamethylenedithio)dialanine product as a residue. The separated product residue was washed with water to remove byproduct, and, after standing overnight, the resulting product was suspended in an additional amount of water at room temperature. The suspension was carried out under nitrogen with concentrated ammonium hydroxide being added in an amount to obtain a clear solution. Potassium cyanide (15 grams) was then added to the solution and the solution stirred for onehalf hour under nitrogen. The product was reprecipitated by portionwise addition to glacial acetic acid to a pH of 5. The resulting precipitated product was separated by filtration, washed with water, and dried by evaporation under subatmospheric pressure at a temperature of C. The product thus obtained melted at 240245 C. Elemental analysis was conducted and the following results obtained.

Calculated: Carbon, 50.50; Hydrogen, 8.48; Nitrogen, 7.36; Sulfur, 16.85. Found: Carbon, 51.36; Hydrogen, 8.18; Nitrogen, 6.79; Sulfur, 15.85.

Example 2.Di-n-butyl 3,3-(decamethylenedithio) dialanine dihydrochloride 2,2 (decamethylenedithio)dialanine (20.0 grams; 0.0525 mole) and 400 milliliters of n-butanol were mixed. Dry gaseous hydrogen chloride was bubbled into the resulting mixture over a period of 4.5 hours and with cooling to a temperature of about 0 C. Thereafter the reaction mixture was heated to reflux temperature and maintained thereat for a period of about 6 hours. The reaction mixture was permitted to stand overnight at room temperature and then reheated to reflux temperature and maintained thereat for an additional two hours. The reaction mixture was again permitted to stand overnight at room temperature. Thereafter, the reaction mixture was placed on a hot water bath and excess n-butanol and hydrochloric acid removed by evaporation under subatmospheric pressure to obtain the desired di-nbutyl 3,3-(decamethylenedithio)dialanine dihydrochloride product as a liquid residue. The product residue was mixed with 200 milliliters of fresh n-butanol and the n-butanol removed by evaporation under subatmospheric pressure. This process was repeated; upon trituration with diethyl ether, the product precipitated and was separated by filtration. The separated product was dried in a vacuum oven and found to melt at 8287 C. Elemental analysis was made and the following results obtained.

Calculated: Carbon, 51.88; Hydrogen, 7.26; Nitrogen, 5.04; Sulfur, 11.54. Found: Carbon, 50.88; Hydrogen, 8.52; Nitrogen, 4.97; Sulfur, 11.18.

In view of the foregoing teachings and examples, those skilled in the art will be enabled to prepare all of the other products of the present invention. Representative such other products include the following: dimethyl 3,3- (decamethylenedithio)dialanine dihydrobromide, molecular weight of 570.5; diisopropyl 3,3'-(decamethylenedithio)dialanine, molecular weight of 464.7; diethyl 3,3- (decamethylenedithio)dialanine dihydrochloride, melting point, 178 C.; di-sec-butyl 3,3'-(decamethylenedithio)dialanine, molecular Weight, 492.8; and 3,3-(deca methylenedithio)dialanine dihydriodide, molecular weight of 636.4.

The products of the present invention, as above noted, are useful as agents to control the growth of plants. In such applications, the unmodified products can be employed; however, it is generally preferred that the product or products be employed in the form of a composition comprising the product or products and one or more adjuvants, such as surface-active agents, inert finely-divided solids, water or organic solvents, and the like. In representative operations, there was prepared a bacteriological culture medium comprising 0.05 percent of di-n-butyl 3,3- (decamethylenedithio)dialanine dihydrochloride; the surface of the medium was inoculated with Candida pelliculosa; another culture medium having no test compound was similarly inoculated to serve as check. Both media were incubated at 30 C. for seventy-two hours and then examined for microorganisms. In the check, the surface of the medium supported a heavy growth of Candida pelliculosa, whereas the medium containing the di-n-butyl 3,3 (decamethylenedithio)dialanine dihydrochloride, there was a complete absence of Candida pelliculosa organisms. Essentially the same results were obtained when diethyl 3,3-(decamethylenedithio)dialanine dihydrochloride Was evaluated in these same procedures.

Also as noted previously, the products of the present invention are useful in vapor phase chromatography. In such application, one or more of the products is taken up in solution in a solvent, and the solvent solution intimately and thoroughly mixed and stirred with an amount of chemically cleaned diatomaceous earth representing from about twenty to about four times the weight of the product or products of the present invention; solvent is removed by vaporization to obtain a treated infusorial earth uniformly coated with and bearing a deposit of the product or products. With repulverization if necessary, the treated infusorial earth is then filled under suction and with the aid of sonic vibration into a coiled otherwise empty column for use in vapor phase chromatography at temperatures at which the product or products of the present invention are mechanically stable. The chromatographic separations upon such column, with the product or products of the present invention functioning as substrate, are useful in research procedures.

6 I claim: 1. Compound of the formula R-O-C-CH-CH -S- u I 2 o NH 2 lovreralkyl-O- t C IH- GH -S- o Na 2 or hydrohalide addition salt thereof wherein the hydrohalide is hydrachloride, hydrobomide or hydriodide.

4. The composition of matter claimed in claim 3 wherein loweralkyl represents ethyl and hydrohalide designates hydrochloride, namely diethyl, 3,3-(decamethylenedithio) dialanine dihydrochloride.

5. The composition of matter claimed in claim 3 wherein lowerulkyl represents n-butyl and hydrohalide designates hydrochloride, namely di-n-butyl 3,3-(decamethylenedithio)dialanine dihydrochloride.

References Cited UNITED STATES PATENTS 3,330,855 7/1967 Braus et a1. 260470 JAMES A. PATTEN, Primary Examiner. EDWARD GLEIMAN, Assistant Examiner.

U.S. Cl. X.R. 

